/usr/lib/python2.7/dist-packages/ClusterShell/MsgTree.py is in clustershell 1.7-1-1.
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# Copyright CEA/DAM/DIF (2007-2014)
# Contributor: Stephane THIELL <stephane.thiell@cea.fr>
#
# This file is part of the ClusterShell library.
#
# This software is governed by the CeCILL-C license under French law and
# abiding by the rules of distribution of free software. You can use,
# modify and/ or redistribute the software under the terms of the CeCILL-C
# license as circulated by CEA, CNRS and INRIA at the following URL
# "http://www.cecill.info".
#
# As a counterpart to the access to the source code and rights to copy,
# modify and redistribute granted by the license, users are provided only
# with a limited warranty and the software's author, the holder of the
# economic rights, and the successive licensors have only limited
# liability.
#
# In this respect, the user's attention is drawn to the risks associated
# with loading, using, modifying and/or developing or reproducing the
# software by the user in light of its specific status of free software,
# that may mean that it is complicated to manipulate, and that also
# therefore means that it is reserved for developers and experienced
# professionals having in-depth computer knowledge. Users are therefore
# encouraged to load and test the software's suitability as regards their
# requirements in conditions enabling the security of their systems and/or
# data to be ensured and, more generally, to use and operate it in the
# same conditions as regards security.
#
# The fact that you are presently reading this means that you have had
# knowledge of the CeCILL-C license and that you accept its terms.
"""
MsgTree
ClusterShell message tree module. The purpose of MsgTree is to provide a
shared message tree for storing message lines received from ClusterShell
Workers (for example, from remote cluster commands). It should be
efficient, in term of algorithm and memory consumption, especially when
remote messages are the same.
"""
from itertools import ifilterfalse, imap
from operator import itemgetter
# MsgTree behavior modes
MODE_DEFER = 0
MODE_SHIFT = 1
MODE_TRACE = 2
class MsgTreeElem(object):
"""
Class representing an element of the MsgTree and its associated
message. Object of this class are returned by the various MsgTree
methods like messages() or walk(). The object can then be used as
an iterator over the message lines or casted into a string.
"""
def __init__(self, msgline=None, parent=None, trace=False):
"""
Initialize message tree element.
"""
# structure
self.parent = parent
self.children = {}
if trace: # special behavior for trace mode
self._shift = self._shift_trace
else:
self._shift = self._shift_notrace
# content
self.msgline = msgline
self.keys = None
def __len__(self):
"""Length of whole message string."""
return len(str(self))
def __eq__(self, other):
"""Comparison method compares whole message strings."""
return str(self) == str(other)
def _add_key(self, key):
"""Add a key to this tree element."""
if self.keys is None:
self.keys = set([key])
else:
self.keys.add(key)
def _shift_notrace(self, key, target_elem):
"""Shift one of our key to specified target element."""
if self.keys and len(self.keys) == 1:
shifting = self.keys
self.keys = None
else:
shifting = set([ key ])
if self.keys:
self.keys.difference_update(shifting)
if not target_elem.keys:
target_elem.keys = shifting
else:
target_elem.keys.update(shifting)
return target_elem
def _shift_trace(self, key, target_elem):
"""Shift one of our key to specified target element (trace
mode: keep backtrace of keys)."""
if not target_elem.keys:
target_elem.keys = set([ key ])
else:
target_elem.keys.add(key)
return target_elem
def __getitem__(self, i):
return list(self.lines())[i]
def __iter__(self):
"""Iterate over message lines starting from this tree element."""
# no msgline in root element
if self.msgline is None:
return
# trace the message path
path = [self.msgline]
parent = self.parent
while parent.msgline is not None:
path.append(parent.msgline)
parent = parent.parent
# rewind path
while path:
yield path.pop()
def lines(self):
"""
Get the whole message lines iterator from this tree element.
"""
return iter(self)
splitlines = lines
def message(self):
"""
Get the whole message buffer from this tree element.
"""
# concat buffers
return '\n'.join(self.lines())
__str__ = message
def append(self, msgline, key=None):
"""
A new message is coming, append it to the tree element with
optional associated source key. Called by MsgTree.add().
Return corresponding MsgTreeElem (possibly newly created).
"""
if key is None:
# No key association, MsgTree is in MODE_DEFER
return self.children.setdefault(msgline, \
self.__class__(msgline, self, self._shift == self._shift_trace))
else:
# key given: get/create new child element and shift down the key
return self._shift(key, self.children.setdefault(msgline, \
self.__class__(msgline, self,
self._shift == self._shift_trace)))
class MsgTree(object):
"""
MsgTree maps key objects to multi-lines messages.
MsgTree is a mutable object. Keys are almost arbitrary values (must
be hashable). Message lines are organized as a tree internally.
MsgTree provides low memory consumption especially on a cluster when
all nodes return similar messages. Also, the gathering of messages is
done automatically.
"""
def __init__(self, mode=MODE_DEFER):
"""MsgTree initializer
The `mode' parameter should be set to one of the following constant:
MODE_DEFER: all messages are processed immediately, saving memory from
duplicate message lines, but keys are associated to tree elements
usually later when tree is first "walked", saving useless state
updates and CPU time. Once the tree is "walked" for the first time, its
mode changes to MODE_SHIFT to keep track of further tree updates.
This is the default mode.
MODE_SHIFT: all keys and messages are processed immediately, it is more
CPU time consuming as MsgTree full state is updated at each add() call.
MODE_TRACE: all keys and messages and processed immediately, and keys
are kept for each message element of the tree. The special method
walk_trace() is then available to walk all elements of the tree.
"""
self.mode = mode
# root element of MsgTree
self._root = MsgTreeElem(trace=(mode == MODE_TRACE))
# dict of keys to MsgTreeElem
self._keys = {}
def clear(self):
"""Remove all items from the MsgTree."""
self._root = MsgTreeElem(trace=(self.mode == MODE_TRACE))
self._keys.clear()
def __len__(self):
"""Return the number of keys contained in the MsgTree."""
return len(self._keys)
def __getitem__(self, key):
"""Return the message of MsgTree with specified key. Raises a
KeyError if key is not in the MsgTree."""
return self._keys[key]
def get(self, key, default=None):
"""
Return the message for key if key is in the MsgTree, else default.
If default is not given, it defaults to None, so that this method
never raises a KeyError.
"""
return self._keys.get(key, default)
def add(self, key, msgline):
"""
Add a message line associated with the given key to the MsgTree.
"""
# try to get current element in MsgTree for the given key,
# defaulting to the root element
e_msg = self._keys.get(key, self._root)
if self.mode >= MODE_SHIFT:
key_shift = key
else:
key_shift = None
# add child msg and update keys dict
self._keys[key] = e_msg.append(msgline, key_shift)
def _update_keys(self):
"""Update keys associated to tree elements (MODE_DEFER)."""
for key, e_msg in self._keys.iteritems():
assert key is not None and e_msg is not None
e_msg._add_key(key)
# MODE_DEFER is no longer valid as keys are now assigned to MsgTreeElems
self.mode = MODE_SHIFT
def keys(self):
"""Return an iterator over MsgTree's keys."""
return self._keys.iterkeys()
__iter__ = keys
def messages(self, match=None):
"""Return an iterator over MsgTree's messages."""
return imap(itemgetter(0), self.walk(match))
def items(self, match=None, mapper=None):
"""
Return (key, message) for each key of the MsgTree.
"""
if mapper is None:
mapper = lambda k: k
for key, elem in self._keys.iteritems():
if match is None or match(key):
yield mapper(key), elem
def _depth(self):
"""
Return the depth of the MsgTree, ie. the max number of lines
per message. Added for debugging.
"""
depth = 0
# stack of (element, depth) tuples used to walk the tree
estack = [ (self._root, depth) ]
while estack:
elem, edepth = estack.pop()
if len(elem.children) > 0:
estack += [(v, edepth + 1) for v in elem.children.values()]
depth = max(depth, edepth)
return depth
def walk(self, match=None, mapper=None):
"""
Walk the tree. Optionally filter keys on match parameter,
and optionally map resulting keys with mapper function.
Return an iterator over (message, keys) tuples for each
different message in the tree.
"""
if self.mode == MODE_DEFER:
self._update_keys()
# stack of elements used to walk the tree (depth-first)
estack = [ self._root ]
while estack:
elem = estack.pop()
children = elem.children
if len(children) > 0:
estack += children.values()
if elem.keys: # has some keys
mkeys = filter(match, elem.keys)
if len(mkeys):
yield elem, map(mapper, mkeys)
def walk_trace(self, match=None, mapper=None):
"""
Walk the tree in trace mode. Optionally filter keys on match
parameter, and optionally map resulting keys with mapper
function.
Return an iterator over 4-length tuples (msgline, keys, depth,
num_children).
"""
assert self.mode == MODE_TRACE, \
"walk_trace() is only callable in trace mode"
# stack of (element, depth) tuples used to walk the tree
estack = [ (self._root, 0) ]
while estack:
elem, edepth = estack.pop()
children = elem.children
nchildren = len(children)
if nchildren > 0:
estack += [(v, edepth + 1) for v in children.values()]
if elem.keys:
mkeys = filter(match, elem.keys)
if len(mkeys):
yield elem.msgline, map(mapper, mkeys), edepth, nchildren
def remove(self, match=None):
"""
Modify the tree by removing any matching key references from the
messages tree.
Example of use:
>>> msgtree.remove(lambda k: k > 3)
"""
# do not walk tree in MODE_DEFER as no key is associated
if self.mode != MODE_DEFER:
estack = [ self._root ]
# walk the tree to keep only matching keys
while estack:
elem = estack.pop()
if len(elem.children) > 0:
estack += elem.children.values()
if elem.keys: # has some keys
elem.keys = set(ifilterfalse(match, elem.keys))
# remove key(s) from known keys dict
for key in filter(match, self._keys.keys()):
del self._keys[key]
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